The invention relates generally to techniques for loading data to an electronic postage meter from an external servicing device, and particularly for techniques for loading data efficiently by taking into account the length of the data to be loaded and the repetitive nature, if any, of the data.
Although electronic postage meters have been commonplace for many years, the predecessor mechanical postage meter is still in use. In a mechanical postage meter a descending register indicative of the amount of postage available to be printed is contained in a mechanical register of gears and other moving parts. A postage printing device is mechanically linked to the mechanical register, and the two are located in a secure housing. Protection against inadvertent or intentional printing of postage in excess of the amount available for printing is found in the security of the housing, the ease of visual detection of tampering, the relative immunity of the mechanical register to vagaries of electric power, and the positive nature of the mechanical linkage between the printer and the register.
Mechanical postage meters have some drawbacks, among them that it is time consuming to change the function of the meter. Many mechanical meters have customization details such as an initial setting of internal register components. Changing the initial setting is a purely mechanical matter calling for the use of tools and in many cases the partial or complete disassembly of the meter. Many other operating parameters and customization details of the meter are quite incapable of change by mechanical modification due to limitations in the mechanical design.
In electronic postage meters it is well known to use a processor executing a stored program to bring about many of the functions of the postage meter that would have been accomplished by mechanical means in a mechanical meter. As with mechanical meters circumstances arise from time to time in which it would be desirable to be able to change a customization detail or other operating parameter. This may be done, for example, by partially or completely disassembling the postage meter, removing some or all of the stored program or related data, and installing new or different stored program or related data. This has the drawback that it is labor-intensive and time-consuming. Because many of the steps are mechanical in nature such actions may shorten the expected service life of the postage meter. Thus attempts have been made in recent years to develop ways permitting updating of stored program or related data without requiring partial or complete disassembly of the postage meter. Although some updating and modification is possible through the keyboard, many recent attempts have been made to effect it by data communication from an external servicing device. In prior art systems, typically the external servicing device sends a packet to the postage meter. The packet contains selection information, sometimes called a "combo digit", indicative of which of a highly constrained universe of possible items are to be changed based on the contents of the packet.
In one prior art system, that of U.S. Pat. No. 4,528,644 to Pitney Bowes, the selection information indicates one of less than a dozen possible items to change. The postage meter has a routine that receives the selection information and, depending on the selection information, determines to store the data in a corresponding particular address. For each of the less than a dozen changeable items, there is an address in the stored program of the postage meter to which data may be loaded.
Such prior art systems are necessarily somewhat inflexible. For a given item in the memory to be changeable by the external servicing device, it has to be the case that the stored program that was earlier provided in the postage meter must include that item in its short list of items that are possible to change.
Such prior art systems are necessarily somewhat slow in the case of a large amount of repetitive information that is to be stored. They typically require that every byte to be loaded must pass individually over the serial line connecting the external servicing device and the postage meter.
There is thus a need for a flexible way to change and update information in the postage meter, overcoming the above-mentioned problems.